Struct MapTypeExtra

Source

pub struct MapTypeExtra {Show 18 fields
    pub layout: MapLayout,
    pub key: u64,
    pub elem: u64,
    pub group: u64,
    pub hmap: Option<u64>,
    pub hasher: Option<u64>,
    pub group_size: Option<u64>,
    pub slot_size: Option<u64>,
    pub keys_off: Option<u64>,
    pub key_stride: Option<u64>,
    pub elems_off: Option<u64>,
    pub elem_stride: Option<u64>,
    pub elem_off: Option<u64>,
    pub key_size: Option<u8>,
    pub value_size: Option<u8>,
    pub bucket_size: Option<u16>,
    pub raw_flags: Option<u32>,
    pub flags: MapFlags,
}

Expand description

Parsed extra fields for a map type descriptor.

Fields absent from the descriptor’s MapLayout are None so callers can tell “this Go version does not record it” from a genuine zero.

Fields§

§layout: MapLayout

Which layout the descriptor was parsed with.

§key: u64

Virtual address of the key type descriptor.

§elem: u64

Virtual address of the element type descriptor.

§group: u64

Virtual address of the bucket (hmap) or slot-group (Swiss) type descriptor.

§hmap: Option<u64>

Virtual address of the hmap type descriptor (MapLayout::HmapWithHmapType only — Go 1.11 removed the field).

§hasher: Option<u64>

Virtual address of the key-hashing function. None for Go 1.11-1.13, which had no hasher field.

§group_size: Option<u64>

Size of a slot group in bytes (GroupSize). Swiss layouts only.

§slot_size: Option<u64>

Size of one key/elem slot (SlotSize). MapLayout::Swiss only — Go 1.27 replaced it with the explicit stride fields below.

§keys_off: Option<u64>

Offset of the keys array within a group (KeysOff). MapLayout::SwissSplitGroup only.

§key_stride: Option<u64>

Stride between consecutive keys (KeyStride). MapLayout::SwissSplitGroup only.

§elems_off: Option<u64>

Offset of the elements array within a group (ElemsOff). MapLayout::SwissSplitGroup only.

§elem_stride: Option<u64>

Stride between consecutive elements (ElemStride). MapLayout::SwissSplitGroup only.

§elem_off: Option<u64>

Offset from a key to its element within a slot (ElemOff). Present in both Swiss layouts.

§key_size: Option<u8>

Size of a key slot in bytes (KeySize). hmap layouts only.

§value_size: Option<u8>

Size of a value slot in bytes (ValueSize / elemsize). hmap layouts only.

§bucket_size: Option<u16>

Size of a bucket in bytes (BucketSize). hmap layouts only.

§raw_flags: Option<u32>

Raw flags word. None for the pre-1.12 layouts, which encoded the same properties as separate booleans. Bit meanings differ between the hmap and Swiss eras — prefer Self::flags, which normalizes them.

§flags: MapFlags

Semantic flags, normalized across all three encodings.

Implementations§

Source §

impl MapTypeExtra

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pub fn size(ps: u8, layout: MapLayout) -> usize

Binary size of the extra for the given pointer size and layout.

Every layout is pointer_fields * ptrSize followed by an 8-byte tail — either four small integers plus four booleans, or u8 + u8 + u16 + u32, or (Swiss) a u32 padded out to pointer alignment. That comes to pointers * ps + 8 on 64-bit and pointers * ps + 8 on 32-bit for the hmap layouts, and pointers * ps + 4 (+4) for the Swiss ones.

Source

pub fn parse(data: &[u8], ps: u8, layout: MapLayout) -> Option<Self>

Parse from data, which must start at the map type’s extra fields (i.e. just past the embedded abi.Type).

A MapLayout::Probe layout is resolved against these bytes first, so the returned Self::layout is always a concrete variant.

Returns None if the buffer is too small for the resolved layout.

Source

pub fn key_stride(&self) -> Option<u64>

Byte stride between consecutive keys in a bucket / group, however the descriptor’s layout happens to record it.

SwissSplitGroup states it directly as KeyStride; Swiss uses the key/elem SlotSize as the stride for both; the hmap layouts pack keys of KeySize contiguously in the bucket. None when the descriptor did not carry the value.

Source